They're the biggest secret in the bird world - but they're noisy buggers!
We had Koels around the home I grew up in, but I never knew what they were. They have a loud, distinctive call, but they're very difficult to spot.
I used to be in a wildlife rescue group, and one day I had to rescue and injured Koel. I thought I knew my birds, but I'd never seen one of these! It was a revelation. I had to look up my bird book to see what they were, who they were like, what they ate, how they lived. They're fascinating.
And around my home now are Koels. I hear them often but see them rarely. We have a awning thing (a frame with sarlon mesh stuff that comes off the house and protects us from the strong western summer sun) and twice a Koel has got stuck under the awning and I've assisted them on their way out - but didn't take a photo! Once I took a photo, but you couldn't recognise the mess as a bird (it wasn't a good shot!). And then the other week, I heard them and they had squawking young. It took a while but I scored this photo of one of the young ones.
Koels are large birds, bigger than a Currawong, and are related to cuckoos.
Now, this is how my bird book (Pizzey's A Field Guide to the Birds of Australia) describes the calls: Males utter a repeated far-carrying 'kooeel'. Also brisk rising 'quoy-quoy-quoy-quoy', falsetto 'quodel-quodel-quodel' or slightly mad rising 'weir-weir-weir-weir!' Females: shrill four-note brassy piping.
Once again, the Australian Museum website has great information, including this on breeding.
The Common Koel is a brood parasite, that is, it lays its eggs in the nests of other bird species. Common hosts are the Red Wattlebird, friarbirds, the Magpie-lark, and figbirds. A single egg is laid in the host's nest and once hatched the chick forces the other eggs and hatchlings out of the nest. When the chick leaves the nest it roosts in the outer branches of a tree, cheeping incessantly while the significantly smaller parents desperately search for sufficient food to satisfy the nagging youngster. This is a full-time job, as the young Koel will grow to nearly twice their size. Eventually, it migrates northwards, usually later than the adults, to return as a breeding bird the following spring.